Questions about delicious plum jam

I bought a bunch of Damson plums at the farmers market the other day, and last night I got around to making jam. I've made a fair amount of jam this summer, and I understand that preserved foods with lots of sugar are not very likely to go bad. But I had a little mishap-- which I don't think is serious-- but enough to make me hope there are some other preservers here who have a little more experience and/or scientific insight.

Frankly, I just always follow the recipes on the box of Sure-Jell. Except last night (later than I would have liked- Damson plums are damned small and took forever to chop), after I had added all the ingredients and was in the final cooking stage, I realized that the recipe said, "6 1/2 cups of cooked plums" not "cook 6 1/2 cups of plums". Hmmm. I suppose they cook down a fair amount in volume in five minutes-- eliminating most of the airspace between the bits of raw chopped plum, for one thing.

I am assuming that because I had too little plum to the proportion of Sure-Jell and sugar (low sugar version), that the worst problem I am likely to encounter is that my jam may be a bit tar-like. But that I have not upset the balance of sugar/fruit that my mother always told me made jam a safe food to preserve even for a non-expert (unlike, say, green beans, which have neither sugar nor acid content and spoil more easily and which my mom always froze rather than canned).

That got me to thinking. The Sure-Jell instructions emphasize not to change a thing. But what are the parameters? I'm really not one for following a recipe exactly. I assume I can add little bits of lemon juice/zest. What are the limits with regard to jelling (jamming?), and with regard to safety (not spoiling and not needing to be refrigerated)?

Or, it you prefer, just tell me your best recipe!

My triumph for the summer is apricot jam, to which I added a bit more lemon juice and zest than the sure-jell called for, and which is just fabulous.

Blue Damson plums tend to be higher in acid, pectin and tannin but lower in sugar than other plums, so they make a very stiff jam when using the proportions in regular Sure-Jel directions. These composition differences are also why Blue Damsons are normally cooked with sugar rather than eaten out of hand.

I tend to prefer half and half Blue Damson and Stanley Prune for preserves, which may require prepping the Blue Damsons and then freezing them without cooking but with the addition of a very little bit of Fruit Fresh to retard browning. I usually pit and quarter the smaller plums (eight pieces for larger) and then chop with a few pulses in the food processor. The volume shrinkage on cooking is minimal and largely offset by the 1/2 cup of water added for cooking. Coarser hand chopping would yield a larger volume difference between raw and cooked and would risk some plum juice loss. Regular Sure-Jel calls for six cups of cooked plums. I use seven and increase the sugar proportionally to keep the proper fruit/sugar ratio. Packaged pectin has some assumptions about the fruit than may not apply to your fruit. Blue Damson and most prune plums have higher acidity and pectin than many other types of plums and so tend to jell pretty stiffly. Acid is important in the jelling reaction over and above any preservative effect, so adjustment may be needed when the acidity of fruit differs from the level assumed by the pectin manufacturer. Red Haven peaches and most midseason Michigan strawberries need some extra acid to jell firmly, particularly when making freezer jam. I have found that adding one teaspoon of citric acid to the sugar per pouch of Certo does the trick for these freezer jams.

I would not worry about being a little low on the amount of plums as far as safety is concerned, but the jam may be tough to spread.

I am a huge jam maker and would suggest tossing the gelatins and trying a cored apple instead. It works beautifully for low pectin fruits. Any amount of fruit can be turned into jam (2-3 qts at a time yields the best results at home--larger quantities push you to over cook the fruit) I usuallly add less around 1/2 the amount of sugar (fruit 4 cups/sugar 2 cups).
This depends somewhat on how sweet the fruit is. Good luck!

Last time I did Damson Plum Jam I got sauce! Which by the way, everyone loved anyway. This year I just took the little buggers and poured sugar and a couple liters of Vodka over them. In three months I'll have something to keep me warm!

Thanks all, this is exactly the feedback I was looking for!

I take it from your responses that I have been unnecessarily paranoid about safety. The instructions on the Sure-Jel must be so strict more so that the stuff gells and no one asks for their money back... If I am not crazed about the consistency, I can be a little more creative in the proportions, I take it. My biggest fear has always been safety, and not wanting to poison anyone-- but I'm getting the idea that the margin on that is much more forgiving than I was thinking (if I put in half a cup too little sugar, watch out!?)

An apple, eh? Any particular kind of apple? Any jam-making books I should think about buying? I made so much jam this summer, I'd really like to learn a little more and feel freer to experiment. (I have no idea which fruits have more or less pectin; I guess I have some idea about acid, but it is not always obvious, eh.)

Now as to the vodka: I happen to have quite a few Damson plums left over, and would be happy for some particulars. I've never been a fan of vodka, I'm actually pretty ignorant about it. What about brandy or rum? Or is the point that vodka is flavorless? And the final product-- something you eat, or spoon over ice cream, or drink, or what? I'm intrigued but need more information...

Judy H wrote:I take it from your responses that I have been unnecessarily paranoid about safety. The instructions on the Sure-Jel must be so strict more so that the stuff gells and no one asks for their money back... If I am not crazed about the consistency, I can be a little more creative in the proportions, I take it. My biggest fear has always been safety, and not wanting to poison anyone-- but I'm getting the idea that the margin on that is much more forgiving than I was thinking (if I put in half a cup too little sugar, watch out!?)

With jams and jellies, you don't really need to worry much about what can go wrong, because if it does go wrong, it will be obvious. Either the stuff won't gel (in which case you can refrigerate it and use it as syrup), or it will get moldy after storage, in which case you toss it. A waste of time, effort and ingredients, but nobody's going to eat obviously moldy jam, so it's not risky.

The preserving risk comes with canning low-acid foods, typically vegetables, which can harbor Clostridium botulinum spores that are both deadly and not easily detectable.

Judy H wrote:Any jam-making books I should think about buying? I made so much jam this summer, I'd really like to learn a little more and feel freer to experiment. (I have no idea which fruits have more or less pectin; I guess I have some idea about acid, but it is not always obvious, eh.)

Here are some useful sites for basic preserving info:
National Center for Home Food Preservation
Jarden Home Brands
Sure-Jell

Beyond the basics, local author Madeleine Bullwinkel offers some interesting recipes in Gourmet Preserves Chez Madelaine. I recommend the blueberry jam with mint.

You can add any type of liquor that you want. This year I tried everclear. A liquor store employee told me that in using everclear I would not get any other taste than just from the plums. A bonus was that one could dilute a bottle of everclear with water to get the same alcohol content of Vodka. What you end up with is a sweet dessert type of liquor. This year I took a large glass jar, and layered damson plums with sugar cubes. Then I poured the everclear (diluted) over it all and put a lid on the jar. I really like using the sugar cubes this year as opposed to just granulated sugar. The sugar cubes went into solution very quickly. Let the whole thing sit for about three months. Remove the plums, stems, and whatever else is floating around, and fill decorative or empty wine bottles and cork. This makes for a great holiday gift. You can dress it up with a personalized label and ribbon. One caution, do not press the plums for the extra juice. This just muddies the liquor, and sometimes it even makes it sort of lumpy. Now, if anyone has any suggestions for using the leftover liquored up Damson plums I'd sure like to hear it. I tried making a fruit bread out of it, but it wasn't that special. Have fun!

Razbry, I can't speak to plums, but last year I used liquored cherries and a bit of their liquor (a gift, so I don't know their exact process) in a glaze for my Easter Ham.

That sounds like one good glaze! I have made many types of liquors over the years. Some take longer than others. I've done raspberry (of course), apple, blueberry, really just about any fruit. There are lots of instructions to the various liquors on the net.